Leetcode 树 Maximum Depth of Binary Tree

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Maximum Depth of Binary Tree

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Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

题意：求给定的一棵二叉树的最大深度

思路：dfs递归。树的最大深度=max(左子树的最大深度，右子树的最大深度) + 1

复杂度：时间O(n)（因为每个节点都要访问一次），空间O(log n)(因为递归压栈要保存root指针，栈最大为log n)

相关题目： Minimum Depth of Binary Tree

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int maxDepth(TreeNode *root) {
        if(root == NULL) return 0;
        return max(maxDepth(root->left) , maxDepth(root->right))  + 1;
    }
   
};